The present invention relates in general to soldering machines and in particular to a new and useful soldering machine which includes a pair of spaced apart guide profiles that extend along a path carrying a succession of a fluxer, a multistage preheater and a solder bath, for soldering circuit boards, and wherein the guide profiles are provided with cooling ducts for cooling and distributing heat evenly between the guide profiles.
In a soldering machine of the species in question, one guide profile may be arranged laterally above the succession of fluxer, preheater and solder bath, whereas the other, adjustable guide profile must be located above the succession of fluxer, preheater and solder bath to adapt the distance between the two guide profiles to the dimensions of the printed circuit boards to be guided by the soldering fingers over the fluxer, preheater and solder bath. In standard soldering machines the adjustment path of the adjustable guide profile relative to the fixed guide profile is up to about 400 mm.
In the operation of the soldering machine, the adjustable guide profile is heated considerably more by the succession of fluxer, preheater and solder bath, but in particular by the heat action of the preheater, than the fixed guide profile located essentially laterally next to the succession of fluxer, preheater and soldering bath. This stronger heating of the adjustable guide profile results in a lengthening of the adjustable profile and this has disadvantageous effects in different ways. For one thing, the running speed of the revolving chain passed around the adjustable guide profile changes, so that a non-parallel conduction of the circuit boards at the soldering fingers of the fixed and of the adjustable guide profiles takes place, resulting in defects of the contact connections to be soldered due to the oblique soldering. In addition deformation of the soldering finger conduction occurs under the action of heat. This heating adversely affects the lateral displacement of the adjustable guide profile. This transport displacement, therefore, may tend to jam.